Activiteit: Gesprek of presentatie › Lezing en mondelinge bijdrage
Species specific responses to environmental stressors and limited dispersal capacity are two important characteristics that make free-living nematode species suitable bioindicators. Although morphological identification of nematodes is too cumbersome for routine monitoring programs, this tedious process may be circumvented using next generation sequencing. Promising studies have shown the usefulness of metabarcoding for meiofauna diversity research at higher taxon level, yet diversity assessments with species-level resolution remain one of the most challenging aspects of metabarcoding. During this talk, the promises and pitfalls of the metabarcoding approach for marine nematodes will be discussed using empirical datasets with mock communities and environmental samples. The resolution of different marker genes (18S and COI), of different bioinformatics pipelines (OTU clustering and sequence variants) and of different taxonomic databases are important considerations when applying metabarcoding for monitoring studies. Equally important is the availability of a high quality reference database with species level taxonomic identification. For the environmental samples, OTU clustering and sequence variant pipelines of the 18S data showed considerable overlap in the number of species detected. In contrast, little overlap between species was found when comparing 18S, COI and morphological data but many species unique to the morphological analysis had congeneric species identified using metabarcode data. Our results further show that metabarcoding data separated impacted areas from control areas in a similar way as morphological data, thereby suggesting that metabarcode data can be used in monitoring studies. Finally, we are also exploring the use of primer-free approaches for nematode community characterization.